TRANSPORTATION SECRETARY Stephanie Pollack said she intends to postpone until next summer the selection of a preferred design for the so-called throat section of the I-90 Allston interchange, and may decide to rebuild a deteriorating stretch of the elevated Turnpike in the area and put off action on the larger highway project for at least 5 to 10 years.

Pollack has been reviewing four options for reconstruction of the transportation infrastructure in the throat area between Boston University and the Charles River and said earlier that a preferred design needed to be selected by this fall because of the deteriorating condition of the elevated Turnpike.

But on Wednesday, at a meeting of the Massachusetts Department of Transportation’s Capital Programs Committee, she said she was putting off a decision on the preferred option until next summer. She said the decision to wait would delay the start of construction for at least a year and increase project costs, which are currently hovering around $1 billion. But she said the delay would allow for additional study and possibly provide some answers to questions about the various options that are being considered.

She also came up with a plan B – rebuild the deteriorating elevated Turnpike in the throat area and put off for 5 to 10 years the larger decision about the rest of the throat’s transportation infrastructure. The plan B would also put off the straightening of the Turnpike west of the throat, the construction of a new MBTA station, and the construction of access roads needed to make way for a new neighborhood being planned on a vast stretch of open land owned by Harvard University.

Pollack said her plan B would allow time to build consensus on what to do in the throat area and come up with a financing plan for the larger project. She said on Wednesday that financing for the massive project was in its infant stages.

The secretary acknowledged, however, that going with plan B would mean the Turnpike section in the throat area would get rebuilt and then rebuilt again a second time once the larger project is undertaken.

The Allston I-90 interchange project is one of the state’s biggest transportation projects in decades and the throat area between Boston University and the Charles River has been a sticking point because it’s so narrow. The challenge has been how to rebuild eight lanes of the Turnpike, four lanes of Soldiers Field Road, four rail tracks, and pedestrian and bike paths in a space that’s extremely narrow.

Three options have emerged – rebuilding an elevated Turnpike and putting all of the other elements at ground level, rebuilding an elevated Soldiers Field Road and putting all the other elements at ground level, and putting all elements at ground level.

Pollack said 500 people or groups filed comments on the options and the “vast majority” of commenters – one source said the actual figure was 90 percent — favored the at-grade approach.

The secretary said the feedback has convinced her that the choice is now between the at-grade design and the approach calling for an elevated Turnpike with all of the other elements at grade.

She said both options would cost $1 billion and would take six to seven years to build. She said the chief advantage of the at-grade approach is that it removes an elevated highway between the neighborhood around BU and the Charles River. She said, however, that the at-grade design would have a much greater impact on the Charles River, both during construction and once the work is completed, and could be difficult to permit. She also said the at-grade approach would end up costing about $300 million more because building it would require the temporary shutdown of a rail line allowing access to a commuter rail maintenance facility on the north side of the commuter rail system; with access to that facility shut off during construction, Pollack said, the MBTA would need to build a new maintenance facility to the south of Boston.

Robert Moylan, a member of the Capital Programs Committee, said it appeared to him that elevating the Turnpike would have been the preferred option had not so many members of the public pushed for the at-grade option. “I think that may have been the case,” Pollack responded.

Pollack said she now intends to wait until next summer to make a decision, once more work on the environmental impact report on the project is completed.

She said she is also moving ahead with initial planning for her plan B, which would use some $200 million in available toll funds to repair the elevated section of the Turnpike in the throat area so it can last another 10 to 15 years.

That would allow additional time to o build consensus on the proper throat design and come up with funding for the larger project and a mitigation plan to alleviate commuter concerns. She said she intends to form a special advisory group consisting of representatives of communities and groups likely to be impacted by the massive construction project.

Despite her agency’s focus on the I-90 Allston interchange project for years, Pollack said she has relatively few funding sources for it. She said there is $200 million in available, unrestricted toll funds and another $300 million that could be become available if a transportation bond bill pending on Beacon Hill is approved.

Pollack said her preference would be to not rely exclusively on toll funds to build the project. She said Harvard and Boston also need to step up and provide “substantial contributions.”

Betsy Taylor, a member of the MassDOT board, applauded Pollack’s approach. “Both the city of Boston and Harvard have asserted that because this Allston project is largely on Harvard’s land and within the city’s taxing realm that they should have an outsized say in what is built. That’s fine, but to my eyes one only gets an outsized say if one is willing to contribute financial resources. It does not seem to me appropriate that the tax base of the rest of the Commonwealth should fund something that particularly benefits one university and one city,” she said.

Harvard issued a statement backing the at-grade approach and opposing  decisions that would focus just on repairs to the existing elevated Turnpike  — what the Department of Transportation calls the no-build approach. “The year of public process and visionary design has demonstrated that this project represents a generational opportunity to replace the compromised viaduct, modernize neighborhood circulation, address long-standing traffic impacts, and introduce increased transit opportunities. The potential for this kind of transformation would not have been possible without the substantial contributions Harvard has already made.  To name but one, without the significant investments Harvard made that resulted in the relocation of CSX rail operations from the footprint of the project, the only possible alternative would be the no-build option.  Harvard has made additional direct contributions to the project including added parkland, removal of the Houghton rail spur, and a commitment of up to $58 million in financial support for West Station.”

Rick Dimino, the president and CEO of the business group A Bettter City, which along with the city of Boston has pushed hard for the at-grade approach, said Pollack is wasting time and should adopt the at-grade approach. He said the public comments on the various options show no one wants an elevated Turnpike.

Dimino also said he was surprised at Pollack’s willingness to put off the decision after saying earlier that action was needed quickly because of the deteriorating condition of the current elevated Turnpike. He said Pollack’s plan B was unwise. “Now is not the time to be kicking the can down the road,” he said.